Induced Resistance to Fall Armyworm (Lepidoptera: Noctuidae) Mediated by a Fungal Endophyte

Endophytic fungi living within some grasses have been shown to increase resistance of their host plants to insect herbivores. The hypothesis that endophytes also mediate induced resistance by a grass to an insect herbivore was tested. Perennial ryegrass, both infected and uninfected with the fungal endophyte Acremonium lolii Latch, was artificially damaged by clipping 4 wk after germination. Fall armyworm, Spodoptera frugiperda , J. E. Smith), larvae were fed shoot material of damaged and undamaged plants in a 2-factor (infection status and damage) design. The interaction between the main effects of damage and infection status had a significant effect on pupal mass. Pupae reared on damaged, infected plants weighed less than those reared on undamaged, infected plants. The reverse was tme for uninfected plants. Our results suggest that the endophyte may mediate an induced response by its host grass.